Area Forecast Discussion
Issued by NWS Key West, FL
Issued by NWS Key West, FL
493 FXUS62 KKEY 170733 AFDKEY Area Forecast Discussion National Weather Service Key West FL 333 AM EDT Thu Jul 17 2025 ...New DISCUSSION, MARINE, AVIATION... .DISCUSSION... Issued at 330 AM EDT Thu Jul 17 2025 Composite infrared satellite and derived vorticity analysis places a low-level cyclonic feature centered somewhere in the vicinity of the northern Gulf Coast between Louisiana and the Florida Panhandle. An expansive low-level anticylonic feature dominates the North Atlantic, supporting the mean east to southeasterlies across the Florida Keys and the adjacent nearshore and offshore coastal waters at this early Thursday morning hour. Finally, a well-defined Tropical Upper Tropospheric Trough (TUTT) cell continues to spin just off the Florida East Coast, slowly migrating westward. KBYX Doppler Radar has been relatively active overnight, supported by the aforementioned cyclonic features in close proximity to the Keys. However, a wedge of dry air sampled in the 850-500 mb isobaric layer in the 00z evening sounding at KEY has largely limited the depth of this shower activity, with very few lightning strikes detected in the overnight period. Temperatures are generally in the lower 80s across the Island Chain, with dew points in the seasonably muggy mid to upper 70s. Today will likely mark the final best chances for measurable rainfall for the next several days, as the aforementioned high strengthens in the North Atlantic. Global model forecast soundings highlight formidable mid-level dry air advecting towards the Keys in the freshening east to southeasterlies, and thus elected to nudge rain and thunder chances down to slight levels for tonight through Sunday night. As a secondary, weak high pressure forms in the eastern Gulf, breezes will gradually slacken by late in the weekend into early next week, when more stagnant July conditions can be anticipated. The forecast becomes increasingly complicated for the early to middle of next week. There is at least some numerical weather prediction ensemble member and mean support for a frontal boundary stalling in the vicinity of the Southeast, with possible weak cyclogenesis occurring somewhere along this feature. Meanwhile, yet another TUTT cell is progged to retrograde from the western North Atlantic southwestward into the Gulf. The combination of these features may lead to yet another above normal rainy and thundery period for Monday through mid-week in the vicinity of the Keys, and we will continue to monitor this possible synoptic pattern enfolding. && .MARINE... Issued at 330 AM EDT Thu Jul 17 2025 A strong area of high pressure will build westward across the North Atlantic towards the Florida Peninsula, supporting freshening east to southeast breezes over the next several days. Small Craft Should Exercise Caution headlines will likely need to be posted for portions of the Florida Keys coastal waters beginning as early as this evening, possibly lasting through Friday. As a second, weak area of high pressure builds over the eastern Gulf for the second half of the weekend through early next week, east to southeast breezes will slacken, becoming light to gentle. && .AVIATION... (06Z TAFS) Issued at 330 AM EDT Thu Jul 17 2025 VFR conditions will prevail at EYW and MTH for the 06Z TAF period. Early morning showers are likely to produce brief periods of MVFR CIGs and VIS, but are not sufficient to warrant TEMPO groups at this time. Winds will increase tonight as shower coverage decreases, and gusts are expected after sunset. && .PRELIMINARY POINT TEMPS/POPS... Key West 90 83 90 83 / 40 20 20 30 Marathon 90 83 90 83 / 30 20 20 20 && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...None. && $$ Public/Marine/Fire...BT Aviation/Nowcasts....AJP Data Acquisition.....BT/AJP Visit us on the web at weather.gov/key Follow us on Facebook and Twitter at: www.facebook.com/nwskeywest www.twitter.com/nwskeywest